A London lawyer proposed to his girlfriend mid-air when their AirAsia plane plunged 24,000 feet in just 9 minutes

British lawyer Chris Jeanes proposed to his Australian girlfriend mid-air when their Bali-bound AirAsia aircraft plunged 24,000 feet in just nine minutes, shortly after taking of from Perth, according to NBC News.

AirAsia Flight QZ535, which had 145 passengers on board, lost cabin pressure about 25 minutes after takeoff on October 15 2017, and started to descend rapidly.

Panicked crew reportedly declared an emergency as oxygen masks dropped from the ceiling.

27-year old Jeanes told NBC News that AirAsia flight attendants "sprinted down aisle shouting 'emergency, brace, crash positions'" about 25 minutes after the plane took off from Perth, Australia.

Jeanes, who is an associate at US firm O'Melveny and Myers based in London, had planned to propose to his 28-year-old girlfriend on the Indonesian island, so instead he pulled down his oxygen mask and did it mid-air.

"Luckily she said, 'yes,'" he said. But the couple also made sure to reconfirm while on the ground.

Here's a video of the terrifying moment the oxygen masks dropped.

The plane is understood to have plunged from about 34,000 feet to around 10,000, an altitude at which cabins are pressurised and oxygen masks are no longer needed, according to NBC.

AirAsia said in a statement that the pilot turned back "following a technical issue to ensure the safety of passengers."

"We commend our pilots for landing the aircraft safely and complying with standard operating procedure. We are fully committed to the safety of our guests and crew and we will continue to ensure that we adhere to the highest safety standards."